Mitigate Security Vulnerability in Tails 5.0 : https://tails.boum.org/security/prototype_pollution/index.en.html
>We recommend that you stop using Tails until the release of 5.1 (May 31)
if you use Tor Browser for sensitive information
(passwords, private messages, personal information, etc.).<*
>Security levelYou can change the security level of Tor Browser to disable browser features as a trade-off between security and usability.
For example, you can set the security level to Safest to disable JavaScript completely.
The security level is set to Standard by default which gives the most usable experience.<*
https://tails.boum.org/doc/anonymous_internet/Tor_Browser/index.en.html#security-level
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You may also like to completely disable JavaScript by;
about:config
Search preference name javaset;
javascript.enabled to false
javascript.options.asmjs to false