That’s almost the exact opposite experience for me. Maybe there’s been a more recent update, but I remember searching for specific phrases in decade old messages and the gmail (web site) search would just flat out refuse to show things but I could find them from my phone. I’ll try again, but to be honest, I’ve somewhat given up on google search in general for results that aren’t recent.

The search has been broken for me for a while. I get better results in the iOS mail app. Searching from within gmail will just flat out not show old results.