Pirelli's first tyre testing session of the year was held at Imola after the Emilia Romagna GP, involving Ferrari, Alpine, Alfa Romeo and AlphaTauri.
The Italian Scuderia ran a car featuring the new 18-inch tyres for 2023 on the 227th of April, with championship leader Charles Leclerc completing his duties in the morning and his teammate Carlos Sainz Jr in the afternoon, who unfortunately suffered from engine issues and had to stop mid session.
However, at least two rival teams asked the FIA to investigate a matter, as Sainz was seen completing the test sporting a floor different to the one used earlier by Leclerc.
In addition to that, the floor appeared to feature an under-floor strake, the type of upgrade that is being tested at the moment by F1 teams in order to solve or reduce the porpoising issue.
Recalling the testing rules issued by the FIA, "Cars at these tests must only use components of a specification that have been used in at least one (1) race or TCC [testing of current cars] during the current Championship year."
"These cars must fully comply with the provisions of the Technical Regulations. No test parts, component changes or set-up changes will be permitted which give any sort of information to the Competitor that is unrelated to the tyre test."
"Mechanical set-up changes, driver control changes and component changes are permitted if agreed in advance with the tyre supplier that they are necessary for the correct evaluation of the tyres or to complete the tyre test."
No further action will be taken on the matter, though.
After talks between Ferrari and the F1 authority ahead of the Miami GP to control the car parts to be used on the F1-75, the FIA was allegedly sure that the Scuderia had been completing to all regulations, although there haven't been official announcements.
Apparently, the floor on the testing car was switched midday after suffering damage in the early session, and the "new" spec on the car ran by Sainz had, in fact, already been used before in the season, probably in the Bahrain testing session.