i always guessed this was because of js files being imported inside ts files. Thus even if mongoose has it's types, its not begin recognized.

While exporting I made this changed and everything worked :

export default /** @type {import("mongoose").Model<import("mongoose").Document>} */ (User);

This is my full file :

    import mongoose from "mongoose"

const userSchema = new mongoose.Schema({
    username: {
        type: String,
        required: [true, "Please provide a username" ],
        unique: true
    },
    email: {
        type: String,
        required: [true, "please provide email"],
        unique: true
    },
    password: {
        type: String,
        required: [true, "Please provide a password"]
    },
    isVerified: {
        type: Boolean,
        default: false
    },
    isAdmin: {
        type: Boolean,
        default: false
    },
    forgotPasswordToken: String,
    forgotPasswordTokenExpiry: Date,
    verifyToken: String,
    verifyTokenExpiry: Date
})

const User = mongoose.models.User || mongoose.model("User", userSchema)


export default /** @type {import("mongoose").Model<import("mongoose").Document>} */ (User);