I'm curious, does it also apply to C2 tilemaps? We still have on-going projects developed on C2
Yes, the same thing happens in C2. I’m guessing there’s no strict memory limit there, so you’re probably fine.
Although, the tile data format in C2 is different - each tile is stored separately. For example: "5,5,5,5,5,5,5,..." instead of "100x5".
If you have tilemaps with millions of tiles, your project files can get huge.