I'm noticing that pinned tabs are reappearing over time in Orion's tab bar. I have not pinned these tabs. I don't use pinned tabs at all - I have used them in the past, but I don't use them any more.
The last pinned tab I closed was on September 15th, on yuntrack.com. It's now October 20th, and I've noticed that it's reappeared in Orion's tab bar. The two other pinned tabs to its left are about:blank - I haven't pinned these either.

When I was using pinned tabs, I did have two pinned tabs for email and calendar services in the first two spaces, which are now about:blank.
I haven't yet done a systematic investigation into when these pinned tabs reappear- since I only notice this happen over time, my current working theory is that it's either:
1) when I close and reopen the browser. If it is this, it's not consistent, because I have closed and reopened with no tabs pinned to test this theory, and not noticed these 'ghost tabs' reappear immediately.
2) related to my Macbook sleeping and waking. I often notice these ghost tabs have reappeared when opening the lid of my laptop.
3) related to tab suspension, somehow
I would expect closed pinned tabs to stay closed!
Version 0.99.136-beta (WebKit 622.1.15.19.2)
Sequoia (15)