Cannot generate more than 16M foliage instances

I’ve been painting foliage for my 8K landscape (via Procedural Foliage Spawner) for a few days, but today it suddenly stopped working and gave a warning “Warning: GPU-Scene Instance data overflow detected, reduce instance count to avoid rendering artifacts. Max allocated ID 16928380 (16.144M), instance buffer size: 16M”, after which PIE will flash like crazy, I googled to try to find the answer, I saw this post [GPU Scene instance warning - #4 by glitchered], but there is no answer there. Can anyone give me a hint? My engine version is 5.4.4