Johnson’s position on Ukraine never really changed, except when he joined a lot of other Pubbies into trying to coopt BIDEN’S TACTIC of combining a border bill with the foreign aid bill. Eventually Johnson hopped off, somewhat it appears in the realization that nothing Congress is going to pass in this session will improve the border situation at all while Biden is in office. More likely the opposite, IMO.
At that point, Johnson was faced with either a discharge petition for the disastrous Senate bill, or try to get something with at least a bit of a Pubbie stamp on it up for a vote, and angle for the border as an unresolved problem for the fall election. HR2 is still being sat on by Schumer, anyway...