With Ubuntu Studio, I’ve been trying to move our support and off-topic rooms to Matrix for several years now. It has several advantages, such as being able to post screenshots or paste large amounts of text directly in a message without fear of flooding the room.
This is great when you have a community that starts out as Matrix. However, as @popey pointed out above, the IRC - Matrix bridge is highly volatile and prone to breakage. In #ubuntustudio we recently had a major bridge outage that caused the entire room to be unbridged via portal and plumbing. All Matrix users were unceremoniously ejected from the IRC side and vice-verse. I had to file an issue with the Matrix people and only after nearly a month was the problem resolved but is still unstable.
During that time, I had to post a notice on the Matrix side that the bridge was down and to manually forward all (via a link) users to webchat on Libera. This is because my most knowledgeable users are using IRC and not Matrix, so people seeking support couldn’t get the best support if they tried on the Matrix side.
This aside, there also might an Ubuntu Governance issue here. As far as I know, this type of decision might have to go through the IRC Council as a proposal before it’s decided. How Canonical decides to operate internally is a Canonical affair, but communication within and between the Ubuntu community definitely falls under Ubuntu Governance.