I can reproduce the effect though ...

in a group with default user TZ set to UTC (I know that should not matter)

with my TZ set to UTC

I create a calendar event with TZ UTC to occur at 18:00

The event shows at 18:00 in the calendar but at 10:00 in /feed

 

If I create an event with TZ set to AWST (8 hours ahead of UTC) for 18:00

it shows in my calendar (TZ UTC) correctly as 12:00

 

but in /feed as 02:00

 

If I change my (account) TZ to AWST,

that same event shows in my calendar as 18:00 (AWST)

but still appears in /feed as 02:00

 

Therefore I conclude that events shown in /feed always display in PST and make no adjustment for my (account) TZ setting.