is this a shoudler injury,warmup issue or what?

so ive been going to the gym for like 4 months and ive started doing upprer lower two timeas a week for about 2 months,today was upper day and started it of with flat bench and incline press

i normally do 2 sets of everything 6-8 reps failure,and flat press i normally do 35 kg for 7-8 reps for a working set,and incline bench 30 kg for 5 or barely 6 (i used to do them normally but recently i started doing them on the smoth machine just so i can train to failure safer bc if i were to do them normally,they dont have safety racks),and btw i start my upper day with those two excersises

for a warmup i just do my first flat bench set with just the bar,and when i moive to incline i am already warmed up BUT i dont know why but for this session i forgot to warm up and i just did my 2 working flat bench sets,and i could only do 4 reps and i has a weird injury on my left shoulder (the memes are true) for some reason but i just brusjed it off

when i went to do incline press with a 5kg on each side plus the bar (30kg total) but i couldnt even lift the bar off my chest on the first rep (thank god that smith machines exist) and when i tried to lift it i felt a weird sensation on my shoulder like it was giving up but kinda painfull,but not painfull like someone hit me (i dont know how to explain it) but my right shoulder was completely fine

i didnt do incline bench that day for obvious reasons,and i felt it for the rest of the workout in some excersises but not that much (i felt it more in machine shoulder press btu still not much)

so is this a form issue,shoulder injury,warmup thing or something else?

my next upper day il be sure to warmup to find out if thats the problem,but until then i wanna know whats up