Eurovision is a song contest that hasn't produced a single good song in over a decade where European countries for a moment become every stereotype other countries have about Europe. It's a bureaucratic nightmare of pointless political bickering lightly coated with a layer of gay (Its only saving grace) and ridiculous costumes (This I think is a perversion. Eurovision was best when all the contestants were schlubby 40 year olds singing songs about their kids or their wives back in the 90s and 00s).
Israel gets to be there because their broadcasting infrastructure was set up initially during the mandatory palestine period which meant they got to be in the European broadcasting union. Now that would logically also mean that Palestine should be able to, but hush your mouth those guys are brown.

People think Israel cheated because they did, always have done, and will continue to do so. They have been given systematic unfair favorable treatment, constantly breaking the rules of the contest itself with no repercussion, even when their contestants were directly harassing other contestants. But what's the issue this year specifically is their perennial astroturfing campaign, making big advertisement campaigns to get people to vote for Israel.