Login doesn't work on macOS Safari

Logging into lemmy.ml from Safari (15.5) on macOS (12.4) fails. JavaScript log shows a number of refusals to load content that "do not appear in the connect-src directive of the Content Security Policy".

The actual JavaScript problem is an undefined 'this':

[Error] TypeError: undefined is not an object (evaluating 'this.ws.send')
	(anonymous function) (client.js:2:939924)
	n (client.js:2:1557798)
	Pe (client.js:2:141451)
	(anonymous function) (client.js:2:766722)
	(anonymous function) (client.js:2:766739)
	(anonymous function) (client.js:2:766739)
	a (client.js:2:765675)
	(anonymous function) (client.js:2:767105)
	a (client.js:2:765980)
	(anonymous function) (client.js:2:767105)
	(anonymous function) (client.js:2:766739)
	a (client.js:2:765980)
	(anonymous function) (client.js:2:767407)
	(anonymous function) (client.js:2:766739)
	(anonymous function) (client.js:2:766739)
	(anonymous function) (client.js:2:766739)
	(anonymous function) (client.js:2:1733164)
	(anonymous function) (client.js:2:1733279)
	(anonymous function) (client.js:2:1733424)
	Global Code (client.js:2:1733428)

This failure is relatively recent. Login worked from Safari at least a month ago. Not sure if the problem started with a change in Safari or a change in Lemmy.