Actually, yes they do. It's called tax harmonisation and it prevents countries in the EU from exploiting others, as Ireland clearly has.
Tax policy changes requires unanimous consent from the countries. That is why attempts to push harmonisation of tax rates go nowhere. I think usually the UK also opposes it. With them gone Ireland will be more vulnerable to being bullied into it but for now even the commission press release pretends this isn't about Irelands tax rate or about which country EU based sales are booked in. Logically EU based sales should be booked in the country they happen in and taxed there but that gets in the way of the single market nirvana EU technocrats are trying to push.