I usually have this a few times per day, and I put it down to a crash (memory related?).
It happens for my wife (rarely) on her M1 mac. My son has this happen on Microsoft Teams, on his low spec Intel Mac (with 2 tabs open).
Sometimes it happens repeatedly on a single website.
Sometimes I can't reload the page - I have to copy the address, open a new tab, paste into the address bar and load it there.
It just happened on 0.99.136-beta (WebKit 622.1.15.19.2)
Only extension loaded was 1Password. Low Power Mode is on. 260 tabs across 11 windows across 2 profiles.
macOS Sequoia, 15.6.1 (24G90). Intel i9, 64 GB RAM, very low memory pressure.
