With Lazio's faint Serie A title hopes being dealt a huge blow as they were losing 2-1 against a side battling relegation, a frustrated Patric bit Donati's arm in stoppage time and received a red card.
However, the league's authorities decided further punishment was required due to the nature of the act.
Lazio had come into the match seven points behind leaders Juventus, having lost two of their four matches since the restart following the coronavirus stoppage.
They were almost a goal down inside three minutes when Marco Mancuso saw his stunning effort disallowed by the VAR due to a handball in the build-up and Lazio responding by immediately taking the lead through Felipe Caiceido.
However, Lecce equalised on 30 minutes through Khouma Babacar before Mancuso smashed a penalty way over the bar just before half-time.
But the hosts did take the lead just after the break when defender Fabio Lucioni headed in from a corner and Lazio's misery was complete with Patrics' stoppage-time red card.
Patric will miss games against Sassuolo at home, Udinese away, the top-of-the-table clash with Juve in Turin and the visit of Cagliari. He will be available for selection again for the penultimate game of the season away at Verona.
Later on Tuesday, Juventus failed to extend their lead at the top as they blew a 2-0 lead to lose 4-2 at AC Milan in an extraordinary match at the San Siro.