I won't (nor could) speak as a trumpet player, but I'd like to give my own general answer as a musician.
As many of us, I've been stuck in the last year and a half due to the current pandemic. Not only phisically (as a classical percussionist, I do not own many of the instruments I'd usually play) but even mentally: I struggled with the whole "ok, I should practice... but for what purpose? I'm not gonna play for a lot of time anyway".
Then, that time came. Finally, I got a small gig, and we started rehearsing on last June. I admit: I didn't practice for a long time, not even weekly. For some periods, the only occurrences of actual "playing" were during online lessons. There were months in which I was seriously wondering if music was still part of my future.
That didn't help.
But, then, that "first" gig finally came. I got only a few days notice, so I thought that trying to "get back in the loop" wasn't very practical: there wasn't enough time to seriously "rebuild" something, and - knowing myself - I'd have probably struggled with more psychological issues than technical ones ("Oh, see? You're not as good as you thought you were! Just give up!"). I decided to consider it as an experiment: it was a small gig, I knew I was going to play relatively simple parts, I could afford that.
And you know what? I did.
To my surprise, my sight-reading was much better than I was afraid of (note: I asked for parts, but they didn't send me anything).
My technique wasn't that bad. On the contrary, despite obvious physical limitations caused by the lack of constant practice, I found my playing as well "technically done" (and not because I wasn't used to listening anymore, since I listened to a lot of music in this lockdown time, and I did a lot of depthful listening analysis too).
My overall playing was actually good. And, please believe me, I'm not bragging: friends and colleagues agree that I'm usually too much self-critical.
How is that? Well, obviously I didn't require a perfect technique "fitness" for that gig. But, most importantly, my expertise (as a learner and as much as a teacher) is so deep-rooted thanks to my experience that I was able to overcome any gap in my long lack of practice.
So, how long can you go without practicing?
Well, that depends. Obviously, there are aspects that do require constant practicing. And that can differ depending on the instruments (there are some instrument families for which you "loose more" within the same period of lack of practice). Also, the higher level you get, the finer perception you got: when you're a beginner you hardly get any difference if you were practicing constantly or if you stopped for a couple of days.
That said, I'm clearly not "as good" as I was two years ago.
If you're a sprint racer, you can't expect to be good unless you do your daily training, not to mention if you stop running for months.
BUT, if, for some reason, you stopped for any amount of time, it doesn't mean that you're restarting from scratch.
If your mental training was good, you'll get back there in a very short time. That's because you know how training (and your training) works, you know how to fix problems, how to "debug" issues.
I've known players that struggled if they didn't practice daily, as much as others that were able to play as wonderfully as they were 2 weeks before, even after doing absolutely no practice at all in the meantime.
Another aspect to keep in mind is that we do need rests (just like in the music we play ;-) ). Sometimes, even taking a complete pause for some time is a good thing. It let your body (and mind) rest and elaborate, and when you get back to your instrument you can actually learn something more.
So, finally, keep practicing as much as you can and as much as your practice is actually useful and benefits your playing. But, if you stopped, don't worry about "how bad will I be after that": just go back to practice as soon as you're able to, and focus on that only. Unless you take that "rest" time as an experience about yourself, focusing on "what I should've done" or "what I lost in the meantime" is almost always useless.