Currently lines K604, K608, K610, K614, K615 (which doesn’t exist anymore irl) and K618 in Sweden are tagged with network=flixbus even thought the Flixbus website and clearly states they are operated by other companies.
I could still consider that acceptable tagging if it were not for the fact that these bus companies set their own fares, and develop their own routes. On top of that they also have their own sales meaning Flixbus simply acts as a reseller of their tickets. By that definition almost all public transport in Sweden should be tagged network=SJ but that is clearly incorrect.
Therefore I propose that these lines get changed to have network align with the operator. If the flixbus connection is important enough to be keept then I would do so by creating a Relation:network - OpenStreetMap Wiki
If the buses are green and show the Flixbus string and tickets can be purchased via flixbus website, then ‘network’= ‘Flixbus’ is ok. Operators, i.e. the owners of the buses and employers of the drivers are tagged in ‘operator’.
If they are not run under the Flixbus label (anymore), then the network should either be deleted or changed to the actual operator (if the run more than one line).
I do not have an opinion on the correct tagging here but I would like to try adding some more fact.
As far back as I can remember Y-buss has been operating busses between, Stockholm and the north of Sweden. This is way before I even heard anything about the company Flixbus. So when I found Note: 4330512 | OpenStreetMap I was a bit amazed that Y-buss now had competition. When solving that Note I realized that there actually was just some kind of cooperation.
As far as I can remember there where no signs about Flixbus at Tönnebro, the signs I saw said Y-buss.