Chromium's V8 Optimizer toggle for disabling JavaScript JIT compilation was changed to only disable the 2 higher tiers of JIT compilation while still leaving the baseline JIT compiler enabled. This also caused the device management policy for JIT predating this to change meaning.

They did this because they decided having a toggle which breaks WebAssembly support is unacceptable. We had to revert these changes.

Microsoft Edge implemented a WebAssembly interpreter instead, but it's not open source and there's no ongoing attempt to upstream it to Chromium.

Vanadium disables JS JIT by default and provides a convenient per-site toggle available in the drop down menu next to the URL. We've restored the previous meaning of disabling the JIT so you'll need to add exceptions for sites requiring WebAssembly again.

https://grapheneos.social/@GrapheneOS/112707958275115758

In theory, we could add 4 choices instead of 2: Disabled, Baseline JIT, Baseline JIT + Tier 2 and Full JIT. However, it's likely far too complicated and we're likely going to stick with having it either enabled or disabled. Chromium will hopefully add a WASM interpreter soon...

This is good news:

https://chromium-review.googlesource.com/c/v8/v8/+/5509903