I was able to build a copy of the libgl1-mesa-dri with the Gallium i915 driver enabled, and that fixed the flickering problem on my netbook from that era.
Here's a copy if anyone would like to try https://github.com/wh0/debian-mesa-i915g/releases/tag/22.3.0-1-1 I saw that Fedora had enabled it too: https://bugzilla.redhat.com/show_bug.cgi?id=2100212
