well, first of all, I wouldn't say Japan and UK "dump" US treasury bond when there are less than 10% changes (There were online "rumour" stating Japan sold 1.7 trillion bond, which is impossible as Japan estimated hold 1.1 to 1.2 trillions bonds only) It's quite obviously Japan is doing this to offset the Tariff policy
as for the June debt, they are going to have a bill to raise the debt ceiling, again, GOP control both House, it's very easy for them to do, unless there are significant change to US borrowing status, nothing is going to change in June. Trump policy is hurting US economy in the long term, even if it is possible to have short term effect, this will only show in 3 or 4 years, that's after his term, if GOP remain and the direction unchanged after 2028, maybe, we will have another financial crisis, but this currently is what we refer to as "Market Correction" in response to Trump policy, and again, as I said in the above post, Fed is not going to allow US Dollar to depreciate, and Powell is going to be there until at least May 2026.