The slur (thought to be the words ‘f—ing f—ot') appeared to come from Leafs player Morgan Rielly (watch lower part of screen at :09) below.
Said the NHL: “The NHL is aware of reports that a homophobic slur was used during the Maple Leafs-Lightning game. The league is investigating the incident and will have no further comment until this investigation is completed.”
Some fans are convinced that it wasn't a slur at all. Read this thread:
Rielly is considered an ally to the LGBTQ community.
Maple Leafs general manager Kyle Dubas released a statement on Monday night as well: “The Club is aware of the reports surrounding a homophobic slur used during the Maple Leafs versus Lightning game on Monday night. The issue of homophobia is one the Toronto Maple Leaf Hockey Club strongly condemns and takes very seriously. We are in communication with the NHL and are cooperating fully with their office.”