True, Priti Patel made a complaint about spending on the remain campaign but it was rejected as lacking evidence. But I don't think Priti suggested the breach might be due to illegal donations. I think she just claimed overspend.

The rules on what is permitted could benefit from more clarity but there is a definate "legal" and a definite "illegal" area, as well as a grey "We are not sure" area. The alleged foreign donations are in the "illegal" set.