Timing attacks are a thing and behavior can be correlated by metadata and situational considerations, e.g. Bob only uses his VPN at night, and only for 21 minutes on average. Jane uses her VPN from roughly 830am to 515pm M-F. What do those patterns mean?
But so long as it works and the costs are low, use the VPN constantly. And always check for leaks.
I use Firefox for most purposes, but have chromium on there for anything related to grad school. Which includes, among other things, Office 365 and Outlook Online. On Fedora 38 if it matters.
Used to use Thunderbird with enigmail for PGP back in the day, it was good. The separate browser is fine now, but T bird is a fine option.
I was hoping for the Mr robot guy