Some perspective on the loss of Bristol. Loganair suspended their daily direct BRS-ABZ route last year due to COVID and when things picked up a bit, they tagged a Bristol leg onto the Teesside-Aberdeen flight (so it went ABZ-MME-BRS-MME-ABZ) while the plane could be otherwise waiting at Teesside. This meant that Bristol passengers could still get to Aberdeen (with a wait on the tarmac at Teesside), the Teesside-Aberdeen plane would be more efficient as it would carry more people and as a bonus there was a standalone Teesside-Bristol flight for people to book.
Loganair now feel that it is time to bring back the direct BRS-ABS route but clearly feel that there is little point in running the MME-BRS leg as well (as they need to focus on filling the newly reintroduced direct service and few ex-BRS passengers will choose the stopping service at Teesside over a direct flight).
The MME-BRS route does not appear to stand up in its own right so Loganair instead are now tagging on a Southampton leg onto one of the Teesside-Aberdeen flights (will be ABZ-MME-SOU-MME-ABZ). This means that Southampton locals can now get to Aberdeen without changing planes, the Teesside-Aberdeen flights get a bit of feed from Southampton and Teesside gets a new route as a by-product.
Disappointing of course to lose Bristol (and to not get the Southampton replacement until next year) but this is more about the BRS-ABZ demand than the number of people wanting to fly between Teesside and Bristol.