get time out error

i facing issue with post editing. i get time out error https://snipboard.io/aP8ViU.jpg and after that 503 Service Unavailable The server is temporarily busy, try again later! https://snipboard.io/G2UMDy.jpg
i have tired to deactivate itheme plugin but error not gone. i created topic on wordpress support forum please see- https://ww.wp.xz.cn/support/topic/the-rest-api-request-failed-due-to-an-error-6/

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