While inspecting the code I realize that there is an #[AsMiddleware] attribute I should use:
https://github.com/doctrine/DoctrineBundle/blob/33bec0ed3e858670585eb9285fe003c8b616623e/src/DependencyInjection/DoctrineExtension.php#L226-L238

But still, I also have had these problems before with other auto configurations.

the answer is "it depends".

• when using autoconfiguration based on a dedicated attribute, that attribute often allows to configure the priority directly when the priority is relevant, to keep things simple. In such case, it should be used (that's the best solution).
• when using autoconfiguration based on an implemented interface (which adds the tag with no priority), it depends how the bundle collects the services:
  • if the services are collected using a tagged locator or tagged iterator argument (through #[AutowireLocator] or #[AutowireIterator] when using autowiring, or through tagged_locator or tagged_iterator arguments when using explicit configuration in XML/Yaml), using the #[AsTaggedItem] attribute works to define the priority (it also works to define the index used in a locator btw)
  • if the services are collected by a compiler pass that uses \Symfony\Component\DependencyInjection\Compiler\PriorityTaggedServiceTrait::findAndSortTaggedServices with a TaggedIteratorArgument as its first argument, using the #[AsTaggedItem] attribute works to define the priority (that's actually the reason why the previous point works btw, as the core compiler passes resolving tagged arguments are using that trait)
  • if the services are collected by a compiler pass that uses the PriorityTaggedServiceTrait with a string as its first argument, you cannot control the priority there. You need to define a tag with an explicit priority attribute
  • if the services are collected by a compiler pass that implements its own sorting, it depends of what that compiler pass supports