Raja Jaichand died fighting Muhammad Ghori in Battlefield. More than what anyone today could do.
The myth of his joining hands with Ghori comes from unreliable oral Rasos. The same Rasos which also talk about Jodha Akbar and which also say Prithviraj embraced Islam.

Author of Raso himself doesn't say that his is a work of history (itihas). He instead classifies it as Kalpana and apologizes to readers for any mistakes on his part.
How can any historical personality be damned disregarding all contemporary sources and using this as evidence?

Prithviraj Raso itself says it is a work of fictional poetry (प्रबन्धकल्पना काव्य). It does not claim to be "history" (इतिहास).
Even the author does not want us to take his story literally at face value. He simply narrates a heroic tale

Finally, do you know who his enemies were, according to the text? Yes, his enemies were the Mughals (who did not appear until 1526) according to the text.

Source - trueindology
Indictales
Hindustantimes

https://indictales.com/2020/02/08/the-narrative-that-raja-jai-chand-was-a-traitor-and-he-betrayed-prithviraj-chauhan-is-a-myth-porpagated-by-marxist-historians/

https://m.hindustantimes.com/india/jaichandra-was-not-a-traitor/story-6KmtBdLoxFTHK7SDbA3uYO.html

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