This is my first post here. I'm using Chitubox 1.7.0 (the latest supported by my linux distro QT version). My printer is a Phrozen Sonic Mini 4K, the resin is the Phrozen ABS-Like matte grey. I attached a snapshot with my Chitubox settings. I'm trying to print really small pieces. The small pieces should have a flat surface but it looks deformed, kind of domed and uneven, I attached a few pictures.
What parameter should I adjust? Exposure time? Light off delay? Lifting speed? Or what else?
You need to anchor the edges of your part better to the build plate. As your part faces the constant force of separation between the build plate and the film, you are creating a suction pull around the edges that is greater than the resin can take and it is warping the part.
I would suggest you only print one part as a test. The other parts on the build are exponentially increasing the force of the suction. Manually place 4-6 heavy supports on the outer edges of the part you're printing. It's just a test, and may be throw-away, but it will show you if that resolves the issues.
additionally, you can print that part directly on the build plate with no supports, but you have to adjust your tolerances to accommodate for the 'elephant foot' that you will experience around the base of the build plate. You can do that in the advanced settings.