The law firm alleges that Apple has been selling computers without dust filters, which causes problems to the display and potentially damages the internals. When the machines bring in cold air to keep components cool, in other words, they also bring in a lot of unwelcome dust in the process, the lawyers claim.
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https://www.theinquirer.net/inquirer/news/3067309/apple-is-getting-sued-for-an-alleged-lack-of-dust-filters-in-macs
https://forums.macrumors.com/threads/apple-facing-class-action-lawsuit-over-lack-of-filters-in-macbooks-and-imacs-causing-trapped-dust.2157618/