It is possible to register and login, but then when I try to make a post from the frontend form it is returning Unauthorized even though I am logged in and the token and header is sent correctly from frontend, probably there is a problem with the authentication in the backend.
I tried to find solution, but most of the solutions are from previous versions of Spring and it is not working anymore.
I tried to permit all from that url .requestMatchers(HttpMethod.POST, "/api/new-post").permitAll() and even this isn’t working, it is still showing unauthorized
Here is my code:

class JwtAuthenticationFilter(private val authenticationManager: AuthenticationManager) : OncePerRequestFilter() {
    override fun doFilterInternal(
        request: HttpServletRequest,
        response: HttpServletResponse,
        filterChain: FilterChain
    ) {
        try {
            val jwt: String = request.getHeader("Authorization").substringAfter("Bearer ")
            val authentication = BearerTokenAuthenticationToken(jwt)
            val authResult = authenticationManager.authenticate(authentication)
            SecurityContextHolder.getContext().authentication = authResult
        } catch (e: Exception) {
            response.status = 401
            return
        }
    }

    override fun shouldNotFilter(request: HttpServletRequest): Boolean {
        return request.servletPath.equals("/api/login") ||
                request.servletPath.equals("/api/register") ||
                request.servletPath.equals("/api/home") ||
                request.servletPath.equals("/api/municipalities") ||
                request.servletPath.equals("/api/user/get")
    }
    
}

@Component
class CustomAuthenticationProvider(private val tokenService: TokenService): AuthenticationProvider {
    override fun authenticate(authentication: Authentication): Authentication? {
        if(authentication !is BearerTokenAuthenticationToken){
            return null
        }

        val jwt: BearerTokenAuthenticationToken = authentication
        val token: String = jwt.token
        val userDetails: UserDetails = tokenService.parseToken(token) ?: throw BadCredentialsException("Invalid token")

        val userId = tokenService.getUserIdFromToken(token) // Implement this method to extract userId from the token.

        return UsernamePasswordAuthenticationToken(
            CustomPrincipal(userDetails, userId),
            "",
            listOf(SimpleGrantedAuthority("USER"))
        )

    }

    override fun supports(authentication: Class<*>?): Boolean {
        return BearerTokenAuthenticationToken::class.java.isAssignableFrom(authentication)

    }
}

@Configuration
@EnableWebSecurity
class SecurityConfig(private val customAuthenticationProvider: CustomAuthenticationProvider) {

    @Bean
    fun authenticationManager(): AuthenticationManager {
        return ProviderManager(listOf(customAuthenticationProvider))
    }

    @Bean
    fun jwtAuthenticationFilter(): JwtAuthenticationFilter {
        return JwtAuthenticationFilter(authenticationManager())
    }

    @Bean
    fun filterChain(http: HttpSecurity): SecurityFilterChain {
        http.securityMatcher("/api/**")
            .authorizeHttpRequests { rmr ->
                rmr
                    .requestMatchers(HttpMethod.POST, "/api/login").permitAll()
                    .requestMatchers(HttpMethod.POST, "/api/register").permitAll()
                    .requestMatchers(HttpMethod.GET, "/api/home").permitAll()
                    .requestMatchers(HttpMethod.GET, "/api/municipalities").permitAll()
                    .requestMatchers(HttpMethod.GET, "/api/user/get").permitAll()
                    .requestMatchers(HttpMethod.POST, "/api/new-post").permitAll()
                    .requestMatchers("/api/**").authenticated()
                    .anyRequest().permitAll()
            }
            .sessionManagement { it.sessionCreationPolicy(SessionCreationPolicy.STATELESS) }
            .csrf { it.disable() }

        http.oauth2ResourceServer { oauth2 ->
            oauth2
                .jwt(Customizer.withDefaults())
        }

        http.addFilterAt(jwtAuthenticationFilter(), BasicAuthenticationFilter::class.java)
        return http.build()
    }

}