MONGODB-AWS (AWS IAM) authentication fails instantly in Compass 1.49.15 when relying on the AWS SDK credential chain (no explicit access key / secret / session token entered in the connection form).

Steps to reproduce

1. Have AWS credentials available via the standard credential chain (e.g. an active AWS CLI SSO session), with no explicit keys entered in Compass.
2. Create a connection with Authentication = AWS IAM (mongodb+srv://<cluster>/?authMechanism=MONGODB-AWS&authSource=$external), leaving Access Key ID / Secret Access Key / Session Token blank so the credential chain is used.
3. Connect.

Expected

Compass obtains temporary credentials from the AWS SDK credential chain and authenticates.

Actual

DNS/SRV resolution, TLS, and heartbeats to all three replica-set members succeed (primary discovered as RSPrimary), then the connection fails at the auth step with:

MongoAWSError: (0 , n.YU) is not a function

Stack from ~/.mongodb/compass/*_log.gz:

MongoAWSError: (0 , n.YU) is not a function
    at i.getCredentials (file:///usr/lib/mongodb-compass/resources/app.asar/build/9108.2656c7770e637ea80cfd.renderer.js:1:278578)
    at process.processTicksAndRejections (node:internal/process/task_queues:104:5)
    at async file:///usr/lib/mongodb-compass/resources/app.asar/build/9108.2656c7770e637ea80cfd.renderer.js:1:95253
    at async m.auth (file:///usr/lib/mongodb-compass/resources/app.asar/build/9108.2656c7770e637ea80cfd.renderer.js:1:94889)
    at async E (file:///usr/lib/mongodb-compass/resources/app.asar/build/9108.2656c7770e637ea80cfd.renderer.js:1:421554)
    at async t.connect (file:///usr/lib/mongodb-compass/resources/app.asar/build/9108.2656c7770e637ea80cfd.renderer.js:1:419067)

Notes

• The failure is deterministic and happens before any AWS network call. The error originates in getCredentials inside the minified renderer bundle — (0 , n.YU) looks like a webpack-mangled import whose export was broken at build time, in the AWS SDK credential-provider path. Possibly related to COMPASS-10272 (Cleanup @aws-sdk/client-sts from webpack config).
• The identical connection string works with the plain Node.js driver (mongodb 6.x + aws4 + @aws-sdk/credential-providers) using the same environment credentials — ping and listDatabases succeed. So the cluster, IAM role, and credentials are fine; only Compass's bundle is affected.