Photoshop 26.2 on macos 15.2 uses TOO MUCH ram up to 15-20GB without open files

i dont think its normal when starting using 20GB ram without any files open and ( only from the last update ) and mac start using swap when i have 32GB ram and only 3-4 Chrome tabs

Well, what you describe, as you describe it, is still very much normal.

this started from the last update (26.2) only.. photoshop on my mac and windows never did this again...

This is normal and by design. It's what makes batch processing possible.

Photoshop does not release memory when a file is closed. The memory is reused and recycled, until you quit the application. Re-requesting it from the OS every time would be slow and impractical.

Also, few people realize how much memory is needed for raster image editing - normally much more than any RAM you may have installed. It is normal for RAM to be saturated up to the allocated amount very quickly. There is no such thing as "enough RAM". That's why Photoshop uses a scratch disk to do the heavy lifting. Think of the scratch disk as Photoshop's main memory, with RAM as a cache to hold the most current data only.

Every history state potentially adds the full uncompressed file size, for every open document, with overhead for certain advanced functions. The total scratch size is orders of magnitude bigger than nominal file sizes. RAM is just a small part of this.