That's decongestant nasal sprays folks. They cause rebound sinusitis and you become tolerant to their effects fairly rapidly, (say a week), when you stop it comes roaring back so you re sue more etc , etc.
Steroid nasal sprays ( are they available off script over there ?) are more effective and tolerance isn't an issue. However if you can avoid the allergen in the first place, that's better still.
I had serious problems with almost every commercial decongestant, nasal spray, etc. Even the saline stuff, doesn't always seem "safe."
I have learned over the years, though, that you can mitigate a LOT of the frustrating stuffiness...by just NOT, EVER, sniffing IN. I used to sniff all the time, and I used to have a fair amount of bad allergies and hayfeaver. I did some allergy shots from 2020-2024, which seems to have cured me of the largely year-long stuff. So now my stuffiness, is related to exposures to things.
Over the last few years, after recovering from some severe issues with CA fumes in 2020 and 2021, I've trained myself to not sniff in. I started doing this after reading a rather detailed article (honestly not sure if I bookmarked it or could find it again) that explained exactly how the nose fends off invading particulate, bacteria, virus and fungi (i.e. spores) that cause most of the problems. It was pretty fascinating, but rather "gory" on the details. Suffice it to say, "snot" has some interesting stuff in it, notably these "spherules" that actually capture all that particulate and hold it. NOW...if you sniff in, then, that FIRST LINE of defense, those spherules, then end up in your head, your throat and your lungs. You don't want that. If you DON'T sniff, then they keep doing their job. Once you blow your nose, then the job that front line of defense did, will work its final magic by ensuring all that particulate gets eliminated from your body...not sucked deeper into it.
So, I wear a half-face 3M respirator mask, or a full PAPR. With the PAPR, I have a lot fewer problems, but not zero. I can usually make it through a whole project (say a bowl, or even a couple of pens or so) before having to go in and blow my nose. With the half-face, its either...go indoors fairly often and blow, or...just snot it up and deal with it later.

In any case...you can train yourself not to sniff in, and if you can, then you can eliminate a LOT of the cases where you'll end up stuffed up and miserable. It takes some time and some real dedication, but once you do, you should find that you have a lot fewer cases where you are stuffed for days.
Oh, something else. Even something like Mucinex and related, will actually CAUSE me to get more stuffed up. I used to use that stuff fairly often, thinking it would help. I always thought I went through a certain progression, where I'd get a but stuffy, then use Mucinex and other things like nasal sprays, then things would get worse, then I'd just get SUPER stuffy for days, felt like I was sick...and then finally it would break. I no longer use ANYTHING. EVER. I no longer have the progression. I'll get a little stuffy...stay a little stuffy, for a little while...then it fades. Flonase, in particular...WREAKED HAVOC on me. That stuff was BAD NEWS, and made things WAY worse. Mucinex can actually make things a good deal worse as well, and if you keep taking it, it can keep you worse for a long time. A lot of other decongestants, antihistamines, etc. I've discovered, can make you BE what you think those drugs are supposed to be FIXING. Now that I am no longer chronically stuffed because of allergies, I'm realizing that even when I do have an allergic attack, if I don't sniff in, and I don't pump myself full of OTC drugs and such, the issue remains MILD. The issues become bad ONLY when I use OTC crap. As if...they were designed to screw you up...
So I highly recommend, figuring out, if you can just ditch all the decongestent junk, train yourself not to sniff, blow your nose as often as you can to evacuate all the crap that's causing problems...and live a life of better breathing. It wasn't until I was mostly through my allergy shot regime, that I really learned that, a lot of the problem is in fact the drugs. I never realize just how much the drugs can make things so, so, so much worse. And you can remain really clear most of the time, if you don't sniff. Your nose is trying to protect you with all that runniness, and the moment you sniff, you undo all the hard work your nose did! Blow, don't sniff!